Process of purifying raw cane juice



Mar. 13, 1923.

1,448,421 C. J. G-SORENSEN PROCESS OF PURIFYING RAW CANE JUICE Filed July 22, 1920 Iilter flaps Ill/911301 Patented Mar. 13, 1923.

CARL J. G. sonnivsnm or ran annrirsrnn, sr. onorx, ViRGIN ISLAND-S.

e cs.

Pnoonss or runrryme RAW? CANE JUICE."

Application filed my 22, 1920. Serial No. 598,247.

T 0 all to ham it may 0 mm Be itknown that I, CARL J.

a subject of the King .of Denmark, and a resident of Frederiksted, Island of St; Croix, Virgin Islands, U. A., have, invent ed a new and useful Improvement in Processes of Purifying Raw Lane Juice, of which the following is a specification. v

This inventionrelates to the clarification of the raw juice extracted from, the sugar cane andhas for its partiOQlar 'objectsa very material reduction in the time of treatment, at present required, the substantial elimination of settling tanks in such clarification and a very decided improvement in, the quality of the resultant juice andthe sugarextracted therefrom, aswell as to obtain other advantages hereinafter described.

Heretofore in the process fordefecating, decolorizing or clarifying sugar u1ce, both fromsugar cane and sugar beets, it has been customary, inorder to effect a filtration of all'the juice, to use not only several per cent of milk of lime but also considerable quantitles of other chemicals, including amongst others sulfur dioxid, phosphoric. acid and the like, such for example as described in Patent No. 997,605. Such prior processes,

however, are not only expensive, because of 1 the amount of chemicals and labor involved, 7

but, owing to the time of operation required,

the output was. greatly restrictedas com- 3 pared with a continuous process such as hereinafter described and furthermore the resultant products were often unsatisface.

tory. .7 I

My investigations have led to the discovery that the clarification can be accomplished more thoroughly, as' well asmore economically and expeditiously, if substan-.

lily-invention is fully set forth in the fol;

lowinn: description and drawing, forming a part thereof, in which the figure shown is a dlagrammaticv ew of an apparatus. sultjected to sufiicient pressure relative to the agulating point'of albuminous matter. v 4 From theheater, the juice still containing i ;.able for carrying-out my invention, the same G. Sonnnsnn,

comprising a digesteror heater 1 having an 1nlet2 and outlet 3, which latter communijcates directly with a pressure filter-press 4.

g In carrying out myinvention I preferably. proceed as follows: 1 I

The raw cane juice, in the original condition in which 1t is extracted, is first strained through a coarse ,stralner, for example a plate strainer having about 225 apertures to the square inch each from..03 to ,Ot: in diameter, in order toremove coarse material therefrom without appreciably removing particles, i. e.,, the bagaw I cillio.- The acidity of the juice is then neutralized by temperingnwith. the requisite fect thorough neutralization/of ,the entire mass, and the ,intimateadmixture of the solid and liquidporjtions thereof. i

While I preferably employ milk of lime quantitv of. millcofflime whilel'constantly agitating the liquid with air in orderto efas a neutralizing agent, owing to its cheap-i 3v ness, it will be obvious to those skilled in the art that barlum hydroxide, sodium 4 hydesired, be employed in lieu thereof as, the essential objectof such neutralization is to prevent inversion such as'would occur if the normal acidity of the juice was unneutraL ized prior to suchtreatment.

he thoroughly -mixed and neutralized I 80, dioxide or a like neutralizing agent may, if f juiceis then pumped or otherwise conducted 1 a into an autoclave heater wherein it is subboilingpoint of the liquida-t the pressure :of

operation to prevent theboiling and froth:

ing thereof. For ordinary juice which boils at atmospheric pressure at less'than 101 C., I maintain'a pressure higher thanthat,

corresponding to a boiling point of 102 C'.

and have found that with .a'pressure of forty pounds'per square inch excellentresults are obtained by, my method if thetemperature of the juicein the heateris raisedto be} tween 108 and 110 C. and the juice'is caused to constantly flow thru-the heater enroute to the filter. y'Slhe temperature in" the heater should in noevent be below 70. 0., .the co substantially-all of the original bagaci-llio is pumped directly thru the filter, such for example as, the ordinary plateand frame filter press, preferably without exposure to;

boils readily, is remarkably free from baga-- cillio and foreign impurities, which fact greatly enhancesits keeping qualities, and upon concentration and crystallization pro} duces prime, dry sugar crystals which are exceedingly dense, hard, and of high purity, being especially low in ash, Water, gum and bagacillio content.

Among the further advantages of my process in addition to its simplicity and the absence of the need for employing very substantial quantities or chemicals therein in order to filter all the juice, are the following: I j

1. The'absence of any sedimentation stage reduces"considerably the storage capacity required'in the plant, it avoids the annoyance of re-heating the juice and adding large quantities of additional lime as is often the case when excess cooling occurs, With consequent needless loss of heat, and it effects a considerable saving in the time or treatment required, since in my process the juice can the pumped continuously through the various stages Without necessitating a stoppage of from tWo to three hours time as novv r quired in those processes Where sedimenta= tion is relied upon to separate the scums and sediments.

2. The presence of the bagacillio in the filtering operation is peculiarly advantageous, since thismaterial together with the albumens and insoluble gums constitutes a remarkably eiiec'tive self-contained filtering medium Which, collecting on the filter plates, forms a homogeneouslayer that'prevents the passage or objectionable impurities While beingextremely permeable to the pure juice, especially if a pressure suiiicient to form a hard cake on the filter. plates is employed, for example a pressure of at least fifteen pounds to the square inch.

3. The'protection of the highly heated juice, With its contained impurities, from prolonged exposure to. the oxidizing action or the atmosphere greatly reduceq any tendency to form difiic'ultly removable colored compounds either due to caramelization or otherwise and consequently any necessity for a 'decolorizing treatment With deleterious chemicals is avoided.

4 Owing to the high purity of the juice obtained in my process there is a considerable saving over the present process in the expense required by cleaning the evaporators.

5-. In this process, contrary to expectations When filtering all of the juice, it is possible to secure very thorough clarification of the juice by employing a very small efi'ectivefiltering surface, viz, of but from 110 to 120 square feet per metric ton of juice.

6. The deterioration of the raw sugar itself produced by my method even after long periods or storage, as may be determined by polarization, is minimized. When one considers that in the island of Cuba alone the loss from deterioration of the ravv sugar has been estimated at five inillion dollars per annuin, the importance of this feature can be appreciated such iii1pr'oveinent,due to my process, can be attributed, it is believed, to the extremely low contentv of bagacillio in the raW sugar which see only admits or more efiective sterilization of the juice but also precludes any decomposition being promoted by the catalytic or other action of these fine solid impurities.

7. Owing to the high temperatures Which are maintained in myprocess until the separation or the clear juice from the mud occurs, the sterilization and clarification are very complete and, it has been: found that thereby the stability or keeping qualities or the clarified juice in very materially Y creased.

The expression in the claiins confining the juice against exposure to external atmospheric conditions has reference to the protection of the highly heated juice from the oxidizing action of the atmosphere,

Which is highly deleterious as hereinbefore Having thus described my invention,

What I claim and desire to secure by UQS,

Letters Patent is: j

1. The method of purifying impure sugar cane juice, .fvvliieh consists in subjecting such juice vvhich has been previously rendered substantially neutraland While containing a majority of the fine fibrous particle's existent in the raw juice to a temperature in excess of 70 (1, and a pressure sufficient to pro ventactive ebullition of the nice at such teniperature, then conducting the heated juice Without exposure thereof to the external atmosphere and While still subjected to a pressure suflicient to prevent ebullition thereof, to a filtering medium and releasing the pressure and recovering the resultant effluent juice from said filtering medium.

2. In the method of purifying impure sugar cane juice containing bagacillio and in a substantially neutral condition, the step which consists in heating such juice above the coagulating point of albumen in a closed receptacle and under a pressure sufficient to prevent active ebullition thereof at the temperature of treatment and then conducting such juice without exposure thereof to the external atmosphere and without permitting sedimentation thereof through a filtering medium.

I 3. The method of purifying impure sugar can juice, which consists in subjecting such juice which has been previously rendered substantially neutral and while containing a majority of the fine fibrous particles existent in the raw juice to a fluid pressure of not lessthan 15 pounds per square inch in excess of atmospheric and to a temperature substantially in excess of 100? 0., then conductin the heated juice without exposure thereof to the external atmosphere and without substantial cooling thereof and while still subjected to a superatmospheric pressure through a filtering medium.

4. The method of clarifying impure neutralized sugar cane juice, which consists in filtering impure juice containing a majority of the bagacillio that were normally present in such juice when in a freshly extracted state, while maintaining such juice at a temperature in excess of 70 G. and then recovering the efiiuent juice.

5. The method, which consists in substantially neutralizing the normal acidity of impure juice extracted from the sugar cane containing a majority of the fine sugar cane fibres that were normally present in such juice when in afreshly extracted state, heat ing such juice to a temperature in excess of 70 (1., and; maintaining a super-atmospheric pressure upon the juice throughout the heating treatment, then, prior to the substantial exposure of such juice to external atmospheric conditions, effecting the accumulation of substantially all of the contained fibrous material on a filtering medium which is freely permeable to the liquid juice and repeatedly passing fresh portions of similarly heated juice through such filtering medium andthe'fibrous mass thereon accumulated.

6. In the process of purifying impure sugar cane juice, the steps which consist in heating the impure juice, which has been previously rendered substantially neutral and while still containing a majority of the bagacillio that were normally present in the juice when in a freshly extracted state, to a temperature sufiicient to effect substantial coagulation of the albuminous matters therein and then, while constantly confining the juice against exposure to external atmospheric conditions, subjecting the same to a filtering operation. 1

7. The method of purifying impure sugar cane juice, which consists in subjecting such juice, while still containing a majority of the bagacillio that were normally present in the juice when in a freshly extracted state, to the neutralizing action of sufficient milk of lime to satisfy the acid reacting compounds in said juice, then heating the same to a temperature in excess of 105 0., while under a pressure suflicient to prevent ebullition of the juice and not less than 25 pounds per square inch in excess of atmospheric heatin such juice while the same is flowing, and then, without interrupting the flow of such juice, causing such juice to pass through a filtering medium which is substantially impervious to the bagacillio and readily'permeable to the liquid juice,

while still maintaining a pressure of at least 15 pounds to the square inch in excess of atmospheric upon the juice during such filtration, and then recovering the resultant effluent juice.

Signed at Frederiksted, Island of St. Croix, Virgin Islands, U. S. A., this 8th day of July, 1920.

CARL J. G. .soRENsEN. 

